Because bacteria produce vitamin B12 and fermented foods are generally fermented using bacteria, there are many rumors regarding vitamin B12 being in fermented foods. To my knowledge, no vitamin B12-producing bacteria is required for any fermented food and, therefore, any fermented food that contains vitamin B12 does so via contamination. Because the human colon contains vitamin B12-producing bacteria, it is possible for B12-producing bacterial contamination to occur during food preparation, particularly in places that do not have high levels of cleanliness. To my knowledge, no fermented plant food in Western countries has been found to contain relevant amounts of vitamin B12 analogues.

A 2010 paper from Korea (1) showed that Korean centenarians (people who live to be 100 years old) who ate only small amounts of animal products had normal vitamin B12 levels. The researchers measured the B12 content of plant foods using a biological assay and found many of the fermented foods and seaweeds to contain vitamin B12 analogues, which they considered to be active. They determined that the centenarians were getting about 30% of their B12 from plant foods and that it was a physiologically important amount.

This could be the case, especially given that the subjects ate fermented foods at almost every meal, much of which is homemade kimchi that, according to the researchers, is fermented for at least 10 months.

While this study is very interesting, unless kimchi produced in western countries is reliably shown to lower MMA levels, it would not be wise to rely on it as a significant source of vitamin B12.

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5 Responses to “B12 in Fermented Foods: Korean Centenarians”

Vitamin B12 is produced by micro-organisms in the soil. In the past, root vegetables contained adequate amounts of B12. Today root vegetables are cleaned so well that all traces of B12 are removed. Meat-eaters acquire B12 through micro-organisms living in the animal flesh they eat. Lacto-ovo vegetarians receive B12 through eggs and dairy products. Obtaining enough B12 through a vegan diet is more challenging. Although cases of B12 deficiency are rare, it can cause pernicious anemia, a serious deficiency disease. Confirmed vegan sources include fortified soy milks, other fortified foods, vitamin pills, and Red Star nutritional yeast (T6635 ). Red Star is available at many natural food stores. Other sources which may prove reliable are the surface bacteria on lightly washed organic vegetables, and bacterial activity in the small intestine, but these are not scientifically verified. Long term studies of vegans have detected a very low rate of B12 deficiency. In fact, more meat-eaters than vegans suffer from this deficiency due to problems absorbing B12. The human body stores a 2-7 year supply of vitamin B12. It’s especially important for women to ensure B12 intake when pregnant or breastfeeding. All other vitamins, minerals, fats and carbohydrates are widely found in the plant kingdom. These nutrients can be easily obtained by maintaining variety in a plant food diet. If you have difficulty adapting to a vegetarian diet it may be that your body needs a few months to adjust and detoxify. Try experimenting with a variety of different foods and cooking methods. If you have concerns about a nutrient deficiency, you can always have your blood tested, but rest assured that a varied vegetarian diet lacks no nutrients and is proven to be a powerful health promoting choice. Bon appetit!

The researchers said that the kimchi had more B12 than expected (presumably more than expected given that much of it was made with fish sauce). But these people weren’t vegan so there is no mystery as to how they were getting a lot of their B12 — animal products.

B12 is made by bacteria in the colon of mammals (and possibly other animals), and since feces often ends up in the soil, it is reasonable to think that perhaps bacteria in the soil, especially soil that has feces in it, has B12-producing bacteria. But I have not see reliable evidence for this.

> Other sources which may prove reliable are the surface bacteria on lightly washed organic vegetables,

Definitely not verified, and if it isn’t verified, why say it? And I would highly doubt that bacteria on the surface of vegetables could produce a physiologically significant amount of B12, even if they exist.

> and bacterial activity in the small intestine, but these are not scientifically verified.

Few people in the western world have B12-producing bacteria in the small intestine; if you do, it’s due to an overgrowth of bacteria that shouldn’t be there.

> Long term studies of vegans have detected a very low rate of B12 deficiency.

Not true.

> The human body stores a 2-7 year supply of vitamin B12.

Random assertion.

> It’s especially important for women to ensure B12 intake when pregnant or breastfeeding.

Very true.

I’m not going to respond to the rest, even thought it’s not that simple.